Vane track for hydrodynamic machines



Jan. 16, 1951 w. FERRIS 2,538,193

VANE TRACK F OR HYDRODYNAMIC MACHINES 3 Sheets-Sheet 1 Filed April 10,1944 INVENTOR WALTER FEH'R'IS ATTUHNEY.

Jan. 16, 1951 w. FERRIS VANE TRACK FOR HYDRODYNAMIC MACHINES Filed April10, 1944 3 Sheets-Sheet 2 INVENTOR B, E N R Fm T R A L W W. FERRIS VANETRACK FOR HYDRODYNAMIC MACHINES Jan. 16 1951 3 Sheets-Sheet 5 FiledApril 10, 1944 INVENTOR T TD H N EY.

Patented Jan. 16, 1951 VANE TRACK FOR HYDRODYNAMIC MACHINES WalterFerris, Milwaukee, Wis., assignor to The Oflgear Company, Milwaukee,Wis., a corporation of Wisconsin Application April 10, 1944, Serial No.530,425

This invention relates to hydrodynamic machines of the sliding vane typeand more particularly to the vane tracks which guide the vanes of suchmachines in their inward and outward movements.

The vane track of a hydrodynamic machine includes a plurality ofabutments or bridges, with which the vanes coact to providesubstantially liquid tight seals between the inlet and the outlet portsof the machine, and a plurality of track sections which are arrangedbetween the bridges and form therewith a continuous track upon which theouter ends of the vanes ride during rotation of the rotor. The bridgesare ordinarily arranged in pairs with one bridge of each pair arrangedclose to the periphery of the rotor and with the other bridge spacedfrom the periphery of the rotor when the machine is performing usefulwork, the bridge which is close to the rotor being called the sealingbridge and the bridge which is spaced from the rotor being called thepumping bridge or the working bridge. If all of the bridges arestationary, the displace ment of the machine is constant but thedisplacement may be varied by providing means to move the working bridgeof each pair toward and from the rotor.

Vane type hydrodynamic machines are extensively used as pumps but aproperly designed vane type hydrodynamic machine may function as amotor. When the machine is used as a pump, its rotor is ordinarilyrotated at such a high speed that the centrifugal force is sufficient tokeep the vanes in contact with the track and it is only necessary tohydrostatically balance the vanes. However, if the machine is to beoperated at slow speeds, as by being used as a motor, the centrifugalforce is insufficient to keep the vanes in contact with the track inwhich case the machine is provided with suitable means for positivelymoving the vanes outward such as means for supplying high pressureliquid to the inner ends of the outward moving vanes.

When the working bridges of a machine having two pairs of bridges arespaced from the rotor and the rotor is rotated, each vane will moveinward as its outer end moves from a working bridge toward the adjacentsealing bridge, it will move outward as its outer end moves from thesecond bridge toward the third bridge, it will move inward as its outerend moves from the third bridge toward the fourth bridge and it willmove outward as its outer end moves from the fourth bridge toward thefirst bridge. Each vane thus makes two reciprocations during each revo-21 Claims. (01. 103-136) lution of the rotor and, since the rotor isoften driven at very high speeds, the reciprocations may be very rapid.

If the vane track is so shaped that it forces each vane inward toorapidly, the vane will tend to dig into the track and thus causeexcessive wear of the track or the vane or both. If the A track having asurface so shaped as to cause uniform accelerations and decelerations ofthe vanes would provide an ideal condition which may be approached in aunitary rigid vane track for a constant displacement machine but 'in avariable displacement machine the contour of the track will vary as themovable bridges are moved inward and outward to vary the displacement.

It has heretofore been proposed to provide a hydrodynamic machine with avane track hav ing flexible track sections arranged between the bridgesand to bend the flexible sections as the bridges are moved inward andoutward but the flexibility of one section may be different from that ofanother section and the exact point at which maximum bending takes placeis unpredictable so that the accelerations of the vanes cannot bedetermined with any degree of ac curacy. Also, such vane tracks aredifficult to manufacture, especially for use with long rotors, and itwould be difficult and expensive to prepare to manufacture such tracksin commercial quantities. I

Various other adjustable vane tracks have been proposed but such tracksrequire auxiliary supports and/or are of such contour when adjusted tocertain lengths that they cause the vanes to accelerate and decelerateat rates outside the desired range.

The present invention has as an object to provide an extensible vanetrack which is free from the objectionable characteristics set forthabove.

Another object is to provide vane track having extensible rigid tracksections arranged between the bridges and supported solely by thebridges.

Another object is to provide a vane track hav-' ing a vane guiding ortrack surface which consists entirely of concave and convex circulararcs. I

Another object is to provide a vane track having a track surfaceconsisting entirely of concave and convex arcs which are tangent attheir junctions with each other.

Another object is to provide a vane track in which extensible vane tracksections having con-- cave track surfaces are pivotally connected toadjacent bridges and each bridge has a track surface which is concaveintermediate .its ends but is convex at its ends to provide convextransition curves between adjacent track surfaces.

Another object is to provide an extensible vane track section having acircular track surface and circular telescoping guide surfaces which areconcentric with the track surface.

Another object is to provide a hydrodynamic machine with a vane trackwhich may be adjusted to vary the displacement of the machine and whichhas a radial port for the flow o'f'liqui'd to and from the rotor of themachine.

Another object is to provide an extensible vane track that .may bereadily manufactured.

Other objects and advantages will appear from the descriptionhereinafter given 'of vane tracks in which the invention is embodied.The invention is exemplified by the vane tracks of the "pumps shownsomewhat schematically in the accompanying drawings in which the viewsare as follows:

Fig. 1 is a transverse section through one half of'a pump in which vanetracks constructed according to the invention are incorporated and whichshows the pump-adjusted to maximum displacement and including in itsvane track the "track section shown in Figs. 3-6.

Fig. 2 is a transverse section through the opposite half of a similarpump and shows the pump adjusted to minimum displacement and includingin its vane track the track section shown in Figs. 7-11.

Fig. '3 is a view of the inner. peripheral face of one of the tracksections shown in Fig. l and it includes portions of the bridges towhich that section is connected.

Fig. 4 is an end or edge view showing the two parts of the track section.shown in Fig. 3 separated .from each other.

Fig. .5 is a view of the outersides of the track section ,parts shown inFig. 4.

.Fig. 6 is a transverse .section taken on the line 6-6 .of Fig.5.

Fig. 7 .is an end or edge viewof one of the track .sectionsshown in.Fig. 2,, the view including portions of the bridges to which thesection is pivoted.

.Fig. 8 is a view of the inner faces of the parts shown in Fig. 7.

Fig. 9 is an end or edgeview showing the two parts of 'the track sectionshown in Fig. 8 separated from each-other.

Fig. :10 is a view of the outer sides of the track section parts shownin Fig. 9.

Fig. 11 .is'a transverse section taken on the line II-II of Fig. 8. Fig.12 is .a diagram illustrating a method for determining the lengths ofthe radii of the track surfaces on the bridges and track sections of ahydrodynamic machine such as the pump shown in Fig. '1.

For the purpose of 'ilustration, the invention has been shownincorporated in variable displacement non-reversible pumps but it may asreadily be incorporated in reversible pumps or in motors.

The-pumps shown inFigs. 1 and 2 each have a plurality of vanes Islidable in suitable slots formed radially in a cylindrical rotor 2which is fixed upon a shaft 3 to be rotated thereby. The outer ends ofvanes I engage an endless track upon which the vanes ride when the rotoris rotated. The vane track includes two diametrically opposed sealingbridges 4 and 5, which are fixed in stationary positions close to theperiphery of rotor 2, two pumping bridges 6 and I which are spaced fromthe other two bridges and are adapted to be moved toward and from theperiphery of rotor 2 to vary pump displacement, and four extensibletrack sections each of which is arranged between and connected toadjacent bridges, the track sections shown in Fig. 1 being designated bythe reference numeral 8. Bridge 1 has been shown arranged close to rotor2 to illustrate the position of the parts when pump displacement is zeroand bridge 6 has been shown spaced from rotor 2 to illustrate theposition of the parts when pump displacement is near maximum.

The rotor and the vane track-are arranged between two cheek plates andwithin an annular spacer ring all of which is enclosed in a suitablecasing. For example, the pump shown in Fig. 1 has its rotor and vanetrack arranged inside of an annular spacer ring 9 and between two cheekplates (not shown) which engage opposite sides of ring 9, and the entireassembly is enclosed within a casing ID.

The bridges are closely fitted between the cheek plates and in suitablerecesses formed in the spacer ring, sealing'bridges 4 and 5 being fixedin stationary positions while pumping bridges 6 and 1 are slidable intheir recesses and adapted to be moved inward and outward by anysuitable means to vary the displacement of the pump.

The space between the periphery of rotor 2 and the inner periphery ofspacer ring 9 communicates with two interconnecteddiametrically opposedintake ports II and two interconnected diametrically opposed dischargeports I2 which are arranged adjacent to the periphery of the rotor, onlytwo of the ports being shown. Each port is arranged between adjacentbridges, and liquid seals between adjacent 'ports are provided by thebridges and the vanes in contact therewith.

Since vane type pumps are well known and since a typical pump of thistype is illustrated and described in U. S. Patent No. 2,141,171 to whichreference may be had for details of construction and mode of operation,further illustration or description of the pump is thought unnecessary,it being deemed sufficient to state that, when rotor 2 is rotated in thedirection of the arrow and the pumping bridges are spaced from therotor, the vanes will move progressively outward as the outer endsthereof move along the vane track from a sealing bridge to a pumpingbridge and they will be forced inward by the track as the outer endsthereof move along the track from a pumping bridge to a sealing bridge.

The spaces between the outer ends of the outward moving vanes will befilled with liquid from intake ports I I and, as each vane crosses apumping bridge, the liquid between it and the preceding vane will bedischarged through a port I2.

If the track surface on each track section were of such a length thatone of its ends would abut the end of the track surface on the adjacentsealing bridge when pump displacement was zero and its other end wouldabut the track surface on the adjacent pumping bridge when pumpdisplacement was maximum, one end or the other of the track surface onthe track section would move away from the track surface on the adjacentbridge as the pumping bridge moved in one direction or the other so thatthere would at all times be a gap in the vane track at one or both endsof each track section.

In order that the track sections may be con nected to the bridges andprovide an unbroken path for the vanes, each stationary bridge hasportions It at opposite sides thereof reduced in thickness, each movablebridge has portions I! at opposite sides thereof reduced in thickness,each track section 8 has notches or recesses l8 and I9 formed inopposite ends thereof to-receive reduced portions I6 and I1, and thenotched end portions of each track section are provided with holes 20and 2| to receive pins 22 and 23 by means of which each track section ispivotally connected to adjacent bridges, the notched portions of thetrack section overlapping the reduced portion of the bridges to providean unbroken track surface as shown in Fig. 3.

Each track section 8 includes two principal parts 26 and 21, which havean arcuate T-shaped groove 28 formed therein and extending through theouter periphery thereof, and an arcuate T-shaped guide segment 29 whichis fitted in groove 28. The inner peripheral faces'of parts 26 and 2!are finished to the same radius to provide a smooth track surface forguidingthe vanes and groove 28 is formed concentric with the tracksurface so that guide segment 29 may hold parts 26 and 21 in alinementwith each other while permitting the two parts to move relatively toeach other in a circumferential direction to vary the length of the vanetrack. The arrangement is such that each track section 8 is pivotallysupported at its ends and it is self-supporting inter mediate its ends.Segment 29 is preferably fixed to one of the two parts, such as part 21,as by means of a pin 30.

The adjacent ends of parts 26 and 21 are so shaped as to provide anunbroken path for the vanes as they pass from one part to the other. Forexample, the inner end of part 26 may have two oppositely inclined faces3| which converge upon the centerline of the track and, the inner end ofpart 2'! may be provided with oppositely inclined faces 32 which divergefrom the centerline of the track so that the end of part 21 iscomplementary to the adjacent end of part 26 as shown in Fig. 3. Thisarrangement provides a bearing for nearly the entire width of each vanewhile it passes from one to the other of the two parts of each section.

The vanes move radially when the pump is discharging liquid and theradial accelerations of the vanes must be maintained within certainlimits in order that the outward moving vanes may remain in contact withthe track and in order that the vanes being forced inward by the trackmay not bear so heavily against the track as to cause excessive frictionand wear.

If the track surfaces of track sections 8 and bridges 4, 5, 6 and i wereconcentric] with the rotor, the track would form a perfect circle whenthe displacement of the pump was zero at which time the vanes would haveno radial movement but when the pump was adjusted to maximumdisplacement, at which time the'radial movement of the vanes would bemaximum, the track surface on each track section 8 would form an anglewith the track surface on the adjacent bridge. The accelerations ofthe'vanes riding upon the concave track surfaces may be maintainedwithin the permissible limits but, as each vane passed across the angleat the junction of a track section surface and a pumping bridge surface,its radial movement would be suddenly reversed and hence uncontrolled atthe very instant that it was performing a maximum amount of work. Also,since the bifurcated end of a track section overlaps the reduced portionon the adjacent bridge in order to provide an unbroken path for thevanes, the end of a track section would extend above the track surfaceof the sealing bridge to which it was connected and the end of thatbridge would extend above the track surface of the same track sectionand thereby form obstructions in the path of the vanes when pumpdisplacement was at or near maximum.

In order to prevent damage to either the track or the vane and to keepthe accelerations of the vanes from being excessive, the bridges areprovided with concave track surfaces having a suitable radius, the tracksections are provided with concave track surfaces having preferably sucha radius that the track surfaces of a track section and the adjacentpumping bridge will be tangent at their junction when pump displacementis maximum and the track surfaces of a track section and the adjacentsealing bridge will be nearly tangent at their junction when pumpdisplacement is zero, pivot pins 22 and 23 are arranged as far radiallyoutward as may be convenient within the available space, the concavesurfaces on each track section and the adjacent sealing bridge arejoined by a convex surface when pump displacement is maximum, and theconcave surfaces on each track section and the adjacent pumping bridgeare joined by a convex surface when pump displacement is minimum so thatthe concave track surfaces on a track section and one adjacent bridgeare joined by a smooth transition curve when the track surfaces on thatsection and the other adjacent bridge are tangent or nearly tangent. Theradii of the track surfaces may be determined in a manner to bepresently explained. The transition curve causes the vanes to moveradially as they pass over it but the curve is such that theaccelerations and decelerations of the vanes at this point are wellwithin the permissible limits. With this arrangement, the radialmovement of a vane is very little when it is performing a maximum amountof work, that is, when pump displacement is maximum and the vane ispassing across a pumping bridge.

The convex track surfaces may be formed upon the vane tracks but, forthe purpose of illustration, they have been shown on the bridges and theends of the track sections have been shown chamfered as indicated at 33and 34 in Fig; 4 so that they will not extend above the track surfacesof the bridges.

While vane track section 8 may be formed in any suitable manner, it hasbeen found convenient and economical to employ the method disclosed inPatent No. 2,467,121.

The concave portion of the track surface on each bridge is preferablycircular so that a plu-' rality of bridges may be fastened to a fixtureand the inner faces of all of those bridges first machined, as byboring, and then finished as by grinding to provide a smooth tracksurface on each bridge but it is not necessary that the concave tracksurface on each bridge be an exact circular arc. Each end of each bridgeis rounded 7 as by grinding r otherwise to form a convex surface whichis concentric with the adjacent hole 26 or 2! and is tangent to theconcave surface, the convex surfaces preferably being formed after theconcave surface is finished.

A method for determined the radii of the track surfaces on the bridgesand the track sections of a hydrodynamic machine, such as the pump shownin Fig. l, is illustrated in Fig. 12 in which a sealing bridge and onepumping bridge, such as bridges 5 and I, are shown in the positionsoccupiedwhen pump displacement is zero and the other pumping bridge,such as bridge 5, is shown in the position occupied when pumpdisplacement is maximum.

As shown in Fig. 12, the concave surface on each'bridge has a radius 5|which is slightly greater than the radius of the rotor but the radiusmay be and in practice sometimes is slightly less than thera'dius of therotor. With the radius as shown and with pump displacement at zero, allof the concave surfaces on all of the bridges are concentric with butspaced slightly from the periphery 'cf the rotor and their radii extendfrom a center Ci which is also the axis of the rotor. When apumpingbridge such as bridge 6 is in itsmaximum displacement position, theradii of its cancave surface extend from a center C2 which is spacedfrom center Cl a distance which for convenience is called the stroke ofthe pump and i's equal 'to the distance through which the bridge '6'moves from its zero displacement posi tion to its maximum displacementposition.

The concave track surface on each bridge extends from one to the otherof its two radii that passthr'ough the pivot pins in that bridge. Asshown',- the concave surface 52 of bridge 5 extends fromradius 5% toradius 5| and the concave surface 53 on each of bridges 6 and '1 extendsfrom radius Si to radius 5l The convex track surface on each'end of eachbridge is concentric with the adjacent pivot pin and tangent to theconcave surface at the radius which passes through that pin. Forexample, each sealing bridge, such as bridge '5, has at each end thereofa convex track surface 54 which is tangent to surface 52 at radius 5H or5 l and has a radius 55 which is struck from the center of the adjacentpin 22, and each pumping bridge, such as bridge 6, has at each endthereof 'a convex track surface 56 which is tangent to concave surface53 at radius 5i or 5| and has a radius 51 which is struck from thecenter of the adjacent pin 23;

In order that a track section may have one end of its track surfacetangent to the concave surface on the adjacent pumping bridge when pumpdisplacement is maximum, the track surface on the track section has thecenter of its are located at a point on the radius which extends fromcenter C2 through the adjacent pin in the pumpin bridge and, in orderthat the other end of the track section surface may be tangent to thetrack surface on the sealing bridge, the center .p-ointis located onthat radius equi-distant from the concave surface on the pumping bridgeand a point on the adjacent convex surface on the sealing bridge.

1 As shown, the track surface of track section 8 had a radius 35 struckfrom a center C3 which is located on radius 5| equi-distant from concavesurface 53 and the innermost point on the adjacent convex surface 54 sothat the track surfaceof-track section 8 is tangent to surface 53 atradius 5i and is tangent to convex: surface 54 at a radius 36 whichextends from center through the adjacent pivot pin 22.

The arrangement is such that thevanes have no change in rate of radialmovement as they travel from one track section 8 onto surface 53 andfrom surface 53 onto the next track section 8 at which time the vanesare performing the maximum amount of work. The vanes traveling from asurface 52 to and along a track section 8 will move radially outward andthe vanes traveling along and from a track section 8 to a surface 52will move radially inward and the radially moving vanes will continue tomove radially in the same direction while passing across convex surface54 but at that time the vanes are performing little or no work and theradial accel-' erations and decelerations of the vanes may be readilydetermined and are well within the permissible limits. Theseaccelerations and decal erations may be further reduced by moving pins22 and 23 further outward.

When the pumping bridges are moved inward to reduce pump displacement,centers C2 and C3 will move inward with them, track sections 8 willpivot upon pins 22 and 23 and the track section parts will telescopewith each other to shorten the length of the track. When the pumpingbridges are moved to their zero displacement position, center C2 willcoincid'e'witli' center Cl and center C3 will move close to center C! asindicated by center C3 which is the center of the are on the tracksection 3 which is arranged between bridges 5 and l.

As the pumping bridges move inward, one'end of the concave track surfaceon each track section 8 moves toward concave track surface 52' to reducethe length of the convex transition curve between the two concavecurves, and the other end of the concave track section surface movesvery slowly out of tangency with the ad' jacent surface 53 and intotangency with convex surface 55 which then provides a small convextransition curve between the concave curves but the transition curve onsurface 55 is so short even at zero displacement 'as to be substantiallnegligible. That is, the length of the convex transition curve betweenconcave surface 53 and the adjacent concave track section surface is thedistance between radius 5| and the radius 36* which extends from centerC3 through the ad-" jacent pivot 23, and the length of the convextransition curve between concave surface 52 and the adjacent concavetrack section surface'is the circular when pump displacement is zero,except for the fact that track radius 36 has been made smaller thanbridge radius 5| to produce the tangent conditions of adjacent concaveand convex arcs just described. This shortened track radius 36. causes avery slight radial movement of each vane which hasno significancebecausev the vaneis unloaded at this time.

In the pump shown in Fig.- 1, the intake and:

discharge ports I I and I2 are arranged at one end of the rotor andextend outward axially from re cess 9 according to the usual practice. I-his a r-.

rangernent isentirelynsatisfactory,in pumps of the sizesordinarily usedbut it i sinot at all sat. isfactory in large pumps for the reason t hat' an increase in capacity does not result in a proportional increase inthe area of axial ports.

The volumetric capacity of a vane pump is determined by its peripheralspeed, its stroke and the diameter and length or thickness of its rotor.Since pumps are ordinarily run at the highest practical rotary speed andsince increasing the diameter would increase the rubbing speed, that isthe speed at-which the ends of the vanes slide along the track,increasing either the rotary speed or increasing the diameter of therotor beyond the diameter necessary to provide sufficient metal betweenthe shaft bore and the vane slots is not a practical way to providelarge increases in volumetric capacity. Even if the diameter of therotor could be readily increased, an increase in rotor diameter wouldresult in only 2. proportional increase in displacement but the weightof the pump would increase in accordance with the square of thediameter.

' If the stroke of the pump should be increased enough to cause the pumpto have a large displacement, the vanes in contact with thepumpingbridges would extend so 'far from the periphery of the'rotor that vanesof proper thickness would be bent or broken by the high pressure createdby the pump, the thickness of a vane being limited due to the fact that,when a vane is passing across a pumping bridge, high pressure acts uponthe full area of the inner end of the vane but acts upon only about onehalf of the area of the outer end of the vane so that the pressureacting upon the differential area forces the vane against the bridgeand, if the vane should be too thick, it would be urged against thebridge with such force that excessive wear of the bridge and vane wouldresult and the eificiency of the pump would be reduced. Consequently,increasing the stroke to obtain a large displacement is impractical.

Increasing the length of the rotor causes a proportionalincrease in thedisplacement of the pump but the space between the periphery of therotor and the vane track remains unchanged so that the area of axialports cannot be increased but the flow through the port must increase inproportion to the increase in displacement. Consequently, liquid cannotflow through an axial port to and from the space between the rotor andthe vane track of a large capacity pump without excessive head losses.In fact, a large pump could not draw liquid from an adjacent reservoirthrough an axial port fast enough to keep the space between its rotorand vane track completely filled with liquid.

In order to prevent such head losses in large capacity pumps, radialports such as shown in Fig. 2 are provided. The pump shown in thatfigure has two diametrically opposed intake ports Il two diametricallyopposed discharge ports [2 and four vane track sections 58 whichcorrespond, respectively, to ports I l and I2 and track sections *8,only two of the track sections and only one of each of the pump portsbeing shown in Fig. 2.

Each track section 58 has an opening or port 59 (Fig. 8) which extendsradially therethrough to provide communication between the adjacent portH- or l2 and the space between the rotor and the vane track. Ports 59may readily be made large enough to permit a free flow of liquid to andfrom the rotor and thereby avoid any substantial head loss.

For the purpose of illustration; ports ll and 12* have been shown asextending radially outward through the pump casing Ill but the outerpart of each may extend in any direction as it is only necessary thatthe flow be radial to and through the track section. The radialarrangement of pump ports forms no part of the present invention but isclaimed in a separate application.

Vane track sections 58 are similar to vane track sections 8 in that eachis extensible and is provided in its opposite ends with notches 18 andl9 which correspond to notches I8 and I9 and permit the track section tooverlap reduced bridge portions Ic and H which correspond to bridgeportions it and El respectively, the ends of the track sections beingchamfered and the ends of the reduced bridge portions being providedwith convex track surfaces as'previously explained. Also, track section58 has been shown provided at its ends with holes 2ll and 21* to receivepins 22? and 23 by means of which it is shown connected to the reducedportions 16* and W of adjacent bridges at points spaced the samedistances from the track surface that pins 22 and 23 are spacedtherefrom but in large size pumps each track section is provided at itsends with a longer projection by means of which it is pivoted toadjacent bridges at greater distances from the track surface. I

Each track section 58 includes a pair of principal parts and El and twoarcuate guide segments 62 and 63 which are U shaped in crosssection andhold parts 60 and BI in alinement with each other while permitting themto move relatively to each other in a circumferential direction to varythe length of the vane track.

The adjacent ends of track section parts 60 and 61 are complementary toeach other and so shaped as to provide an unbroken pathfor the end of avane passing along the track surface from one part to the other. Asshown, part 60 has two oppositely inclined end faces 64 and part 6| hastwo oppositely inclined faces '65 which extend from openings 59 toopposite sides of the track.

Each pair of parts and 61 has two grooves 66 and 61 formed in each sideor edge thereof concentric to but spaced from the track surface and fromeach other so as to leave a rib 68 between the two grooves. Each ofguide segments 62 and 63 is made U shaped in cross section and of suchsize and shape that it will fit into grooves 66 and 6'] and rib 68 willfit into the'segment. Two segments 62 and 63 are applied to oppositesides of a pair of parts and fastened, as by means of a pin 69, to onepart, such as part 6|.

The arrangement is such that, when a track section 58 is pivotallyconnected at its ends to adjacent bridges and one of the bridges ismoved relatively to the other to vary the length of the vane track, oneof the track section parts will slide upon guide segments 62 and E3which will keep the two parts in circular alinement so that no supportfor the track section is needed other than the pivotal connection at itsends.

The invention herein set forth is susceptible of various modificationsand adaptations without departing from the scope of the invention whichis hereby claimed as follows:

1. A vane track for a vane type hydrodynamic machine comprising aplurality of bridges and an equal number of extensible vane tracksections formed separately from said bridges and arranged alternatelywith said bridges to form an endless vane track, each of said tracksections connectera's-ass 1 1 ing adjacent bridges to each other andcomprising two parts which telescope with each other so that the lengthof said track may be varied by adjusting one or more of said bridges.

2. A vane track for a vane type hydrodynamic machine comprising aplurality of bridges and extensible vane track sections connectingadjacent bridges to each other and forming with said bridges an endlessvane track, each of said track sections having opposite ends thereofpivoted to adjacent bridges and being divided into two parts whichtelescope with each other so that the length of-said track may be variedby adjusting one or more of said bridges.

3; A vane track for a vane type hydrodynamic machine comprising fourbridges arranged -90 apart, four vane track sections arranged betweensaid bridges and forming therewith an endless vane track, and means forpivotally connecting opposite ends of each section to adjacent bridges,each of said sections comprising two parts which telescope with eachother so that the length of said track may be varied by adjusting two ormore of said bridges.

'4. A vane track for a vane type hydrodynamic -machine comprising fourbridges arranged 90 apart, four vane track sections arranged betweensaid bridges and forming therewith an 'endless vane track, and means forpivotally connecting opposite ends of each section to adjacent bridges,each of said sections comprising 'two parts which telescope with eachother so that the length of said track may be varied by adjusting two ormore of said bridges, and the adjacent ends of said section parts beingso shaped as to provide an unbroken track for the vanes of said machine.

5., A vane track for a vane type hydrodynamic machine comprising aplurality of bridges and extensible vane track sections formedseparately from said bridges and connecting adjacent bridges to eachother to form with said bridges an endless vane track, each of saidtrack sections comprising two parts which telescopewith each other sothat the length of said track may be varied by adjusting one -or more ofsaid bridges, and each of said track sections having "an openingextending radiallythereth'roujgh to provide a port through which liquidma'y'fiow radially to and from the interiorof s'aidin'achine.

6. A'va'ne track for a variefty'p'e hydrodynamic machine compassespluralitybf bridges each 6f which has formed thereon a track surfacewhich is concave intefinediateits'eiids and conadjacent its ends, and a"plurality of track "sections each orwmch is pivotally ccnnected toadjacent bridges and preview with "a "concave "track surface whichtangentatits'ends to the track surfaces onthe'biidge's 'to which it iscannected, each ofsaid track sections'including two relatively movablepartsand said 'mbvable parts being extensible in respect to "eachoth'er'to per- Init one bridge to be a djuste'd whil'etheadjacnt bridgesremain stationary. v

'7. A vane track for 'a'vane type hydrodynamic machine comprising aplurality bf bridges each of which has formed thereon a "tracksurfacewhich is concave intermediate its ends and conve'xadjacent its ends, and"a plurality of track sections each of which is 'pivotally'connected toadjacent bridges and provided with a concave track surface which istangent at its'ends toth'e track surfaces on the bridgestowhich'it'is'com nected, all ofsaid track surracesconsistingentirely ofcircular arcs and each "of said track sections including two relatively"movable p'a'rts 1 2 and said movable parts being extensible in respectto each other to permit one bridge to be adjusted while the adjacentbridges remain stationary.

8. A vane track for a hydrodynamic machine comprising at least one pairof bridges, one bridge of each pair being adjustable to vary thedisplacement of said machine, an equal number of track sections each ofwhich is pivotally connected to adjacent bridges, a concave tracksurface on each track section, a concave track surface on each bridge,and convex track surfaces tangentially connecting adjacent concave tracksurfaces to provide a vane guiding surface smoothly continuous at alldisplacements of said machine, each of said track sections including tworelatively movable parts and said movable parts being extensible inrespect to each other to permit one bridge of a pair to be adjustedwhile the other bridge of that pair remains stationary.

9. A vane track for a hydrodynamic machine comprising at least one pairof bridges, one bridge of each pair being adjustable to vary thedisplacement of said machine, an equal number of track sections each ofwhich is pivotally connected to adjacent bridges, a concave tracksurface on each track section, a co'n'cavetrack surface on each bridge,and convex track surfaces tangentially connecting adjacent concave tracksurfaces to provide a vane guiding surface smoothly continuous "at alldisplacements of said machine, each of said vane track sectionscomprising two parts provided with guide surfaces which arecomplementary to each other and are concentric with the track surfacethereon to make each track section extensible and thereby permit onebridge of apair to be adjusted while the other bridge of that pairremains stationary.

10. In a hydrodynamic machine having vanes arranged substantiallyradially in a rotor and a plurality of bridges arranged around saidrotor and forming'parts of an endless track for said vanes, 'thecombination of an arcuate extensible vane track section connected toadjacent bridges 'and including two track parts each of which isprovided with an arcuate-grooveforming in eifect a continuation of thegroove in the other of said track parts, and an arcuate guide segmentfitte d in said grooves to hold said parts in circumferentialaline'm'ent while permittingone of said adjacent bridges to moverelatively to the other.

11. In a hydrodynamic machine havingvanes arranged substantiallyradially in a rotor and'a plurality of bridges arranged around saidrotor and forming parts of an endless track for said vanes,'thecombination of an 'arcuate extensible vane track section connectedto'adjacent bridges and including two track parts each of which isprovided with anareuete groove'forming in efiect a continuation 6f thegroove in'the other of said track'p'a'rts, and an arcuateguide'seg'fne'nt fitted in said g'r'oove's tohold said-partsincir'cumfe're'ntial alininnt while permitting one of said adjacentbridges to move relatively to the other,th' adjacent 'ends 'of the twoparts'of said section being so shaped as to provide an unbroke'n'trackfor said vanes.

12. In a vane'type hydrodynamic machine having a rotor, the combinationof 'a sealing bridge normally arranged close to said'rotor and having atrack surface'whichis concave intermediate its ends and isconvexadjacentits'en'ds, a working bridge movable toward and fromsaid'rotortovary the displacement of said machine 'b't'wee'n minimum and maximum andhaving a concave track surface formed thereon, and an extensible tracksection including two relatively movable parts and pivotally connectedto both of said bridges and provided with a circular track surfacehaving such a radius that when the working bridge is in its maximumdisplacement position and the sealing bridge is in its normal positionthe track surface on said track section is tangent to the concave tracksurface on said working bridge and is tangent to the track surface onsaid sealing bridge.

' 13. In a hydrodynamic machine having vanes arranged substantiallyradially in a rotor and a plurality of bridges arranged around saidrotor and forming parts of an endless track for said vanes, thecombination of an arcuate extensible vane track section connected toadjacent bridges and including two track parts each of which is providedwith an arcuate groove which is T shaped in cross-section and forms ineffect a continuation of the groove in the other of said track parts,and an arcuate guide segment which is T shaped in cross section fittedin said grooves to hold said parts in circumferential alinement whilepermitting one of said adjacent bridges to move relatively to the other.

14. In a hydrodynamic machine having a rotor and vanes arrangedsubstantially radially in said rotor, the combination of a plurality ofbridges arranged around said rotor, and a plurality of arcuateextensible track sections arranged between and connected to said bridgesto form therewith an endless vane track; each of said track sectionsbeing provided with a radial port for the flow of liquid to and fromsaid rotor and each track section including two track parts one of whichis provided in opposite sides thereof with arcuate grooves havingradially opposed bearing faces and the other of which has arcuate 1guide segments fitted in said grooves to hold the two parts of thattrack section in alinement while permitting relative movement betweenthe two bridges to which that track'section is connected.

15. A vane track for a vane type hydrodynamic machine comprising aplurality of bridges and extensible vane track sections connectingadjacent bridges to each other and forming with said bridges an endlessvane track, the radially inward faces of said sections being finished toa radius less than the radius of said rotor and each of said tracksections comprising two parts which telescope with each other so thatthe length of said track may be varied by adjusting one or more of saidbridges.

16. In a hydrodynamic machine having vanes arranged substantiallyradially in a rotor and a plurality of bridges arranged around saidrotor and forming parts of a track for said vanes, the combination of anarcuate two-part vane track section arranged between adjacent bridgesand provided with an arcuate groove, means for pivotally connectingopposite ends of said track section to said adjacent bridges, an arcuateguide segment fitted in said groove to hold said parts in alinementwhile permitting one of said adjacent bridges to move relatively to theother, and means for fixing said segment to one of said section parts.

1'7. In a hydrodynamic machine having vanes arranged substantiallyradially in a rotor and a plurality of bridges arranged around saidrotor and forming parts of an endless track for said vanes, thecombination of an arcuate two-part vane track section connected toadjacent bridges and having an arcuate groove formed in both parts ofsaid section, and an arcuate guide segment fitted in said groove to holdsaid parts in alinement while permitting one of said adjacent bridges tomove relatively to the other, the radially inward face of said tracksection being finished to a radius less than the radius of said rotor. 1

18. In a hydrodynamic machine having a roto and vanes arrangedsubstantially radially in said rotor, the combination of a plurality ofbridges arranged around said rotor, and a plurality of arcuate two-parttrack sections arranged between and connected to said bridges to formtherewith an endless vane track, the radially inward faces of said tracksections being finished to a radius less than the radius of said rotorand each of said track sections being provided with a radial port forthe flow of liquid to and from said rotor, one part of each tracksection being provided in opposite sides thereof with arcuate grooveshaving radially opposed bearing faces and the other part of that sectionhaving arcuate guide segments arranged upon opposite sides thereof and.fitted in said grooves to hold the two parts of that track section inalinement while permitting relative movement between the two bridges toi which that track section is connected.

19. In a hydrodynamic machine having a rotor and vanes arrangedsubstantially radially in said rotor, the combination of a plurality ofbridges arranged around said rotor, and a plurality of arcuate two-parttrack sections arranged between and connected to said bridges to formtherewith an endless vane track, the adjacent ends of the two parts ofeach track section being so shaped as to provide an unbroken path forsaid vanes and each of said track sections being provided with a radialport for the flow of liquid to and from said rotor, one part of eachsection being provided in opposite sides thereof with arcuate grooveshaving radially opposed bearing faces and the other part of that sectionhaving arcuate guide segments arranged upon opposite sides thereof andfitted in said grooves to hold the two parts of that track section inalinement while permitting relative movement between the two bridges towhich that track section is connected.

20. In a vane type hydrodynamic machine, the combination of a rotorhaving vanes arranged substantially radially therein, a structureenclosing said rotor and provided with passages for the flow of liquidto and from said rotor, and a vane track arranged within said structureand around said rotor to engage the outer ends of said vanes, said vanetrack including a plurality of bridges at least one of which isadjustable to vary the displacement of said machine and a plurality ofextensible vane track sections arranged between and pivoted to saidbridges and having openings of substantial area extending radiallytherethrough to provide communication between said rotor and saidpassages so that liquid may flow radially to and from said rotor andthereby avoid excessive head losses in machines of large capacities.

21. In a vane type hydrodynamic machine, the combination of a rotorhaving vanes arranged substantially radially therein, a structureenclosing said rotor and provided with passages for the flow of liquidto and from said rotor, a plurality of vane track bridges arrangedaround said rotor within said structure, means for adjusting at leastone of said bridges to vary the displacement mgsssnes vane #trac-k:sections connecting .said bridges to each :other to form therewith anendless track for the outer ends of said vanes, each of .said vanevtrack .sections having an opening JOf vsubstantial ,area extendingvradially therethrough to Iprovide communication between said rotor andsaid :passages so that liquid may'flow'radially to and from said rotorand thereby avoid excessive head losses .111 machines oflargecapacities.

WALTER .-F.ERRIS.

REFERENCES CITED Number N umber' 16 UNITED STATES PA'I'ENTS Name DateCentervall Aug. '18, 1942 Wainwright Aug. 3, 1920 Calzoni Oct. 8, 1935Centervall .'Dec. 27, 1938 Kucher May 27, 1941 Kucher Aug. 25, 1942Kendrick et a1 Mar. 9, 1943 Kendrick etal. Mar. 9, 1943 Kendrick Nov.30, 1943 Kendrick Jan. 30, 1945 Ferris Apr. '12, 1949 FOREIGN PATENTSCountry Date Great Britain Dec. '18, 1924 Italy 1939

